Identification and characterization of sialidase-like activity in the developmental stages of Amblyomma variegatum.

Amblyomma variegatum F. are obligate hematophagous ectoparasites of livestock that serve as the vectors of Ehrlichia ruminantium (formerly known as Cowdria ruminantium), the causative agent of heartwater disease. In the light of the fact that they are blood-feeding, their salivary glands play prominent role in their acquisition of nutrients from the bloodmeal. Sialic acids are a major component of glycoprotein in mammalian blood fluid and cells. Sialome of hard ticks is still sparse. Here, for the first time, the possible expression of sialidase in A. variegatum was investigated. Our finding established the presence of type II sialidase-like activity in the three stages (larva, nymph, and adult) of the fed and unfed tick. There was no statistically significant difference in sialidase activity in the various stages of this ectoparasite (P > 0.05). The enzyme was purified by combination of salting out and ion exchange chromatography on DEAE--cellulose and hydroxylapatite columns. Characterization of the enzyme revealed that it is optimally active at 40 degrees C and pH 5.5, and is activated by bivalent cations Zn2+ or Fe2+. The enzyme has a Km of 0.023 mM and Vmax of 0.16 millimol/min with Fetuin as the substrate. To assess the susceptibility of some mammalian cells to the tick sialidase, we prepared erythrocyte ghost cells from different animals, which were incubated with the enzyme. Results revealed that the ruminant cells were better substrates. Our work and findings contribute to the preliminary characterization of the A. variegatum salivary proteome, and may pave way to the development of new acaricides.

Isolation and Structural Elucidation of Novel Antidiabetic Compounds from Leaves of Momordica balsamina Linn and Leptadenia hastata (Pers) Decne.

The antihyperglycemic effect of the polyherbal combination of the leaves of Momordica balsamina Linn (MB) and Leptadenia hastata (pers) Decne (LH) have been reported in our previous study in addition to its documented dietary usages. However, the bioactive principles are yet to be fully elucidated. In the present study, bioactive antidiabetic compounds from the leaf extracts of Momordica balsamina Linn and Leptadenia hastata (pers) Decne were isolated and characterized. The plant leaves were fractionated with solvents in ascending order of polarity (hexane-chloroform-ethylacetate-methanol) using microwave assisted extraction method. The ethylacetate (MBE) and methanolic (LHM) leaf extracts of MB and LH, having the highest antihyperglycemic effects were purified by column chromatography and preparative thin layer chromatography. The antihyperglycemic activity of the isolated compounds was evaluated in streptozotocin (STZ)-induced diabetic rats and the structures of the most bioactive compounds were elucidated by 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy in comparison with reported literature. A pentacyclic triterpenoid (H3) and an isoflavone (LH2b) isolated from MBE and LHM with significant (p < 0.05) antihyperglycemic effects were identified as betulinic acid and 5-methyl genistein respectively. Our study isolated for the first time a triterpenoid and an isoflavone with potential antidiabetic effects from these indigenous antidiabetic plants. This further validates the traditional multi-therapeutic usage of the combination for the management of Diabetes Mellitus (DM) and its complications.

Bioguided fractionation of hypoglycaemic component in methanol extract of Vernonia amygdalina: an in vivo study.

Nine components (C1-C9) were isolated from chloroform fraction of fractionated methanol extracts of Vernonia amygdalina leaves (FMEVA) by column chromatography. All the components C1 to C9 were purified and screened for hypoglycaemic activities in type-2 diabetic rats. The most potent hypoglycaemic component was elucidated on the basis of extensive spectroscopic (1D-, 2D-NMR, GC-MS, FTIR) data analysis. The Component C5 was found to be the most potent hypoglycaemic in reducing blood glucose by 12.55 ± 3.55% at 4 h post-oral administration, when compared to the positive (18.07 ± 1.20%) and negative (-1.99 ± 0.43%) controls. The spectroscopic data analysis reveals that the isolated compound has a structure consistent with 11ß,13-dihydrovernolide. The isolated compound is part of the hypoglycaemic components present in V. amygdalina leaves that is responsible for the anti-diabetic activities. Further research is needed in the development of this compound or its derivatives for pharmaceutical use.

Anti-Diabetic Potential of Ocimum gratissimum Leaf Fractions in Fortified Diet-Fed Streptozotocin Treated Rat Model of Type-2 Diabetes.

Background: Ocimum gratissimum (OG) is used in the traditional management of diabetes in Nigeria. This study investigated the anti-diabetic potential of OG leaf fractions (OGLF) in a rat model of Type-2 diabetes (T2D). Method: Methanol crude extract of OG leaf was fractionated with solvents of increasing order of polarity (n-hexane, chloroform, ethyl-acetate, n-butanol and water). The anti-diabetic potential of the fractions was evaluated in vivo. T2D was induced in Albino Wistar rats and treated with OGLF. Result: The T2D rats showed significant elevation in serum levels of fasting blood glucose (FBG), liver and kidney function biomarkers. At 4-weeks of intervention with OGLF, the untreated diabetic control group maintained severe hyperglycaemia in the presence of 61.7% serum insulin, 17.3% pancreatic ß-cell function (HOMA-ß) and 51.5% Insulin sensitivity. The glucose tolerance ability was enhanced in the n-butanol-fraction (OGb) treated group. With 74.8% available serum insulin and 38.6% improvement in insulin sensitivity, the OGb treated group had a 63.5% reduction in FBG and it was found to be most effective as it ameliorates a majority of the changes caused in the studied parameters in diabetic rats. Conclusions: The data from this study suggest that OGb fraction is a potential candidate for the development of an effective drug for the management of T2D.

Appropriate Insulin Level in Selecting Fortified Diet-Fed, Streptozotocin-Treated Rat Model of Type 2 Diabetes for Anti-Diabetic Studies.

BACKGROUND: Pathophysiological investigation of disease in a suitable animal model is a classical approach towards development of a credible therapeutic strategy. This study examined appropriate insulin level in selecting animal model for type 2 diabetes (T2D) studies. METHOD: Albino Wistar rats (150-200g) were divided into two groups fed with commercially available normal-diet-feed (NDF) and water or fortified diet feed (FDF) (10g NDF per gram of margarine) with 20% fructose solution as drinking water. After 6 weeks of dietary regimen both groups were divided into 5 sub-groups and injected intraperitoneally with a graded dose of streptozotocin (STZ) (0, 25, 35, 45 & 55mg/kg bw.). RESULT: The result showed that the FDF-fed rats increased significantly in body weight, basal serum insulin, total cholesterol, triglycerides and blood glucose levels as compared to NDF-fed rats. Ten days post STZ induction, the groups treated with STZ (45 & 55 mg/kg) developed frank hyperglycaemia with < 46.8% serum insulin, a severe deficiency typical of diabetes type 1. The NDF25 and NDF35 groups with 75.7% and 64.4% serum insulin respectively presented relative normoglycemia, whereas the FDF35 (85.8% serum insulin) were notably hyperglycaemia (>300 mg/dL) throughout the 6weeks post diabetes confirmation. These FDF35 rats were sensitive to glibenclamide, metformin and pioglitazone in lowering hyperglycaemia, hypertriglyceridemia and hypercholesterolemia. CONCLUSION: The hyperglycaemia stability of the FDF35 rats (85.5% insulin) together with their sensitivity to 3 different hypoglycaemic drugs strongly suggests their suitability as a non-genetic model of T2D. Hence the study shows that circulating serum insulin ≥ 85.8% with overt hyperglycaemia may be utilized as the benchmark in selecting rat models for T2D studies.

Cis-vaccenic acid induces differentiation and up-regulates gamma globin synthesis in K562, JK1 and transgenic mice erythroid progenitor stem cells.

Gamma globin induction remains a promising pharmacological therapeutic treatment mode for sickle cell anemia and beta thalassemia, however Hydroxyurea remains the only FDA approved drug which works via this mechanism. In this regard, we assayed the γ-globin inducing capacity of Cis-vaccenic acid (CVA). CVA induced differentiation of K562, JK1 and transgenic mice primary bone marrow hematopoietic progenitor stem cells. CVA also significantly up-regulated γ-globin gene expression in JK-1 and transgenic mice bone marrow erythroid progenitor stem cells (TMbmEPSCs) but not K562 cells without altering cell viability. Increased γ-globin expression was accompanied by KLF1 suppression in CVA induced JK-1 cells. Erythropoietin induced differentiation of JK-1 cells 24h before CVA induction did not significantly alter CVA induced differentiation and γ-globin expression in JK-1 cells. Inhibition of JK-1 and Transgenic mice bone marrow erythroid progenitor stem cells Fatty acid elongase 5 (Elovl5) and Δ(9) desaturase suppressed the γ-globin inductive effects of CVA. CVA treatment failed to rescue γ-globin expression in Elovl5 and Δ(9)-desaturase inhibited cells 48 h post inhibition in JK-1 cells. The data suggests that CVA directly modulates differentiation of JK-1 and TMbmEPSCs, and indirectly modulates γ-globin gene expression in these cells. Our findings provide important clues for further evaluations of CVA as a potential fetal hemoglobin therapeutic inducer.

Ameliorative Effects of Acacia Honey against Sodium Arsenite-Induced Oxidative Stress in Some Viscera of Male Wistar Albino Rats.

Cancer is a leading cause of death worldwide and its development is frequently associated with oxidative stress-induced by carcinogens such as arsenicals. Most foods are basically health-promoting or disease-preventing and a typical example of such type is honey. This study was undertaken to investigate the ameliorative effects of Acacia honey on sodium arsenite-induced oxidative stress in the heart, lung and kidney tissues of male Wistar rats. Male Wistar albino rats divided into four groups of five rats each were administered distilled water, Acacia honey (20%), sodium arsenite (5 mg/kg body weight), Acacia honey, and sodium arsenite daily for one week. They were sacrificed anesthetically using 60 mg/kg sodium pentothal. The tissues were used for the assessment of glutathione peroxidase, catalase, and superoxide dismutase activities, protein content and lipid peroxidation. Sodium arsenite significantly (P < 0.05) suppressed the glutathione peroxidase, catalase, superoxide dismutase activities with simultaneous induction of lipid peroxidation. Administration of Acacia honey significantly increased (P < 0.05) glutathione peroxidase, catalase, and superoxide dismutase activities with concomitant suppression of lipid peroxidation as evident by the decrease in malondialdehyde level. From the results obtained, Acacia honey mitigates sodium arsenite induced-oxidative stress in male Wistar albino rats, which suggest that it may attenuate oxidative stress implicated in chemical carcinogenesis.